This invention is directed to the field of archery, and more specifically to crossbows with features to program the draw weight to optimize the energy and velocity of the projectiles launched from the crossbow. Applicant incorporates by reference Published Application US 2011-0308508, Dec. 22, 2011.
Crossbows that include means to regulate their draw weight typically take the form of compound bow systems, with various cams and cables, which make the crossbows complicated and expensive.
It is an objective of modern crossbows to transfer to the bolt or arrow as much as possible of the energy that is stored in the bow, so that the projectile will fly faster and farther. These goals have been difficult to achieve. Some inefficiencies are due to mechanical losses in the crossover strings and pulley mechanisms that have universally been employed in compound bow systems.
The present invention seeks to obtain the advantages in controlled draw weight characteristics with a crossbow of the recurve limb design, i.e., the type that does not employ crossover cables, synchronizing pulleys or cam wheels on the riser or limbs of the bow.
The invention also seeks to improve the characteristics of the crossbow with a simple pulley system that permits a smaller amount of bend of the power limbs between release and brace.